diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 6ecde95..051d210 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -455,16 +455,16 @@ Drupal.ajax.prototype.beforeSend = function (xmlhttprequest, options) {
     if (this.progress.url) {
       progressBar.startMonitoring(this.progress.url, this.progress.interval || 1500);
     }
-    this.progress.element = $(progressBar.element).addClass('ajax-progress ajax-progress-bar');
+    this.progress.$element = $(progressBar.element).addClass('ajax-progress ajax-progress-bar');
     this.progress.object = progressBar;
-    $(this.element).after(this.progress.element);
+    $(this.element).after(this.progress.$element);
   }
   else if (this.progress.type === 'throbber') {
-    this.progress.element = $('<div class="ajax-progress ajax-progress-throbber"><div class="throbber">&nbsp;</div></div>');
+    this.progress.$element = $('<div class="ajax-progress ajax-progress-throbber"><div class="throbber">&nbsp;</div></div>');
     if (this.progress.message) {
       this.progress.element.find('.throbber').after('<div class="message">' + this.progress.message + '</div>');
     }
-    $(this.element).after(this.progress.element);
+    $(this.element).after(this.progress.$element);
   }
 };
 
@@ -473,8 +473,8 @@ Drupal.ajax.prototype.beforeSend = function (xmlhttprequest, options) {
  */
 Drupal.ajax.prototype.success = function (response, status) {
   // Remove the progress element.
-  if (this.progress.element) {
-    $(this.progress.element).remove();
+  if (this.progress.$element) {
+    $(this.progress.$element).remove();
   }
   if (this.progress.object) {
     this.progress.object.stopMonitoring();
@@ -533,8 +533,8 @@ Drupal.ajax.prototype.getEffect = function (response) {
  */
 Drupal.ajax.prototype.error = function (response, uri) {
   // Remove the progress element.
-  if (this.progress.element) {
-    $(this.progress.element).remove();
+  if (this.progress.$element) {
+    $(this.progress.$element).remove();
   }
   if (this.progress.object) {
     this.progress.object.stopMonitoring();
diff --git a/core/misc/progress.js b/core/misc/progress.js
index e3e000f..7bae81e 100644
--- a/core/misc/progress.js
+++ b/core/misc/progress.js
@@ -4,13 +4,13 @@
 
 /**
  * A progressbar object. Initialized with the given id. Must be inserted into
- * the DOM afterwards through progressBar.element.
+ * the DOM afterwards through progressBar.$element.
  *
  * method is the function which will perform the HTTP request to get the
  * progress bar state. Either "GET" or "POST".
  *
  * e.g. pb = new Drupal.ProgressBar('myProgressBar');
- *      some_element.appendChild(pb.element);
+ *      some_element.appendChild(pb.$element);
  */
 Drupal.ProgressBar = function (id, updateCallback, method, errorCallback) {
   this.id = id;
@@ -33,10 +33,10 @@ $.extend(Drupal.ProgressBar.prototype, {
    */
   setProgress: function (percentage, message, label) {
     if (percentage >= 0 && percentage <= 100) {
-      $(this.element).find('div.progress__bar').css('width', percentage + '%');
-      $(this.element).find('div.progress__percentage').html(percentage + '%');
+      this.$element.find('div.progress__bar').css('width', percentage + '%');
+      this.$element.find('div.progress__percentage').html(percentage + '%');
     }
-    $('div.progress__description', this.element).html(message);
+    this.$element.find('div.progress__description').html(message);
     $('div.progress__label', this.element).html(label);
     if (this.updateCallback) {
       this.updateCallback(percentage, message, this);
@@ -101,7 +101,7 @@ $.extend(Drupal.ProgressBar.prototype, {
    */
   displayError: function (string) {
     var error = $('<div class="messages messages--error"></div>').html(string);
-    $(this.element).before(error).hide();
+    this.$element.before(error).hide();
 
     if (this.errorCallback) {
       this.errorCallback(this);